Flush corrugated fiberboard box joint



Dec. 3, 1968 R. w. LOHEED 3,414,184

FLUSH CORRUGATED FIBERBOARD BOX JOINT Filed June 1, 1967 INVENTOR. RICHAR D W. LOHEE D.

ATTORNE? United States Patent 3,414,184 FLUSH CORRUGATED FIBERBOARD BOXJOINT Richard W. Loheed, West Lafayette, Ind., assignor to InlandContainer Corporation, Indianapolis, Ind., a corporation of IndianaFiled June 1, 1967, Ser. No. 642,741 7 Claims. (Cl. 22948) ABSTRACT OFTHE DISCLOSURE Manufacturers joint for a box formed from a blank ofcorrugated fiberboard having two liners and corrugating mediumtherebetween, the joint being formed between the two adjacent edges of ablank having an inner and an outer liner and intervening corrugatingmedium, one edge of the blank having the liners extended to form lapportions beyond the edge of the intervening corrugating medium, with theinner lap portion of the inner liner being offset outwardly andadhesively bonded to the outer liner to form a lap of the thickness ofboth liners and of substantial width, and the other edge of the blankhaving its outer liner pressed inwardly along the edge for a width atleast as great as the width of the lap, to provide an olfset area, andan offset at least as great as the thickness of the lap, and the lapbeing adhesively secured to the offset area in overlapping relationthereto.

This invention relates to corrugated fiberboard boxes, and moreparticularly to the manufacturers joint.

Corrugated fiberboard boxes, as manufactured by the box maker, generallyconstitute a scored and slotted blank, with the joint between the blankends completed so that each blank comprises a double thickness ofcorrugated fiberboard, each thickness including closure flaps usuallyformed by slots and scored, and two side panels of the box joined alongthe edges by 180 degree folds, the folds or bends being along scoresthat eventually become the diagonally opposite side corners of the boxwhen the box is erected for filling and the 180 degree bends reduced toright angle bends. Centrally located in regard to each thickness of theblank is a second score or fold line, the score lines of the twothicknesses becoming the other diagonally opposite side corners of thebox when erected.

The blanks are formed on a continuous basis, a pair of kraft or otherpaper liners or face sheets being fed into a corrugating machine, tocombine with the corrugating medium produced by the machine to form whatis known as double face board, consisting of two face sheets or linersadhesively secured to the loops or arches of the corrugating mediumtherebetween. The blanks as cut from the double face board are usuallysquared and of a size to provide the necessary four side panels of abox, the closure flaps and any additional seam portion, such as a lap,as may be required, assuming a lap joint is to be effected.

Blanks folded and joined in the flat form are delivered to the customerin bundles of many blanks stacked one upon the other. Where themanufacturers joint is a lap joint, the lap generally results in extrathickness. Such extra thickness in a stack of blanks prevents the blanksfrom lying fiat upon one another, and in a bundle, such extra thicknessat the lap joint produces a bulge. Even the shipping of a bundle of suchblanks entails additional cost due to the bulge of the bundle caused bythe multiplicity of extra thicknesses at the lap joint of each blank.Such shipping costs tend to limit the area that can be competitivelyserved by a manufacturer of such cartons. While lapped joints, whetherglued or stapled, are structurally sound, the lap prevents neat stackingand is unsightly, whether disposed inside or outside.

The present invention is directed to a blank wherein the joint is of thelap type, but in which the joint is flush with surfaces of the facesheets. The joint, in addition, is admirably suited to employment at thebox corner, and the strength of the joint substantially matches that ofa lapped manufacturers joint. More particularly, the joint is formed byextended face sheet seam or lap portions which will serve as a lap inthe joint to be formed, the lap portions having the corrugating mediumremoved from between the face sheets. Thus, the fiap or lap is reducedin thickness to that of the liners alone. In order to compensate forsuch thickness, however, the adjoining portion of the blank is crushedor pressed as by passing between rolls to break the liner connectingportions of the flutes of the corrugating medium, and such pressedportion is allowed to spring back partially to its original thickness,the spring-back being limited, however, by the broken connectingportion, so that the spring-back is short by approximately the thicknessof the two liners to be employed in completing the lap joint. In thismanner, a flush lap joint of great strength and little extra cost iseffected.

The above and other novel features of the invention will appear morefully hereinafter from the following detained description when taken inconjunction with the accompanying drawings. It is expressly understoodthat the drawings are employed for purposes of illustration only and arenot designed as a definition of the limits of the invention, referencebeing had for this purpose to the appended claims.

In the drawings, wherein like reference characters indicate like parts:

FIGURE 1 is a plan view of a blank ready for folding into a tube formaking the joint;

FIGURE 2 is a sectional view taken on the line 22 of FIGURE 4, withparts broken away because of enlargement;

FIGURE 3 is a view of the joint when folded to a right angle; and

FIGURE 4 is a plan view of a finished blank with the joint completed.

Referring to the drawings, there is shown a box blank after having beenslotted and scored, but before the formation of the blank into a jointedflat blank as in FIGURE 4, ready for bundling and shipment to thecustomer. As shown, the blank comprises a series of side wall panels, inthis case of the same. size, as indicated at 22, 24, 26, and 28, suchpanels being identified by scores 23, 25, and 27, which will be locatedat three of the box corners when the box is erected. Each panel hasintegral closure flaps 30 and 32, identified by scorings 34 and 36, suchflaps being separated from one another by slots as at as and 40.

The blank, as shown in FIGURE 1, comprises spaced liners or facingsheets 40 and 42, and intervening corrugating medium 44, as indicated inFIGURES 2 and 3. The blank, before slotting and lap cutting, may consistof a rectangular sheet of double faced corrugated board, as produced bystandard corrugating apparatus, the dimensions of which are the overalldimensions of the blank shown in FIGURE 1.

Assuming the corrugation of the corrugating medium of the blank extendparallel with the scores 23, 25, and 27, the blank, while being fed inthe direction of arrow A, will have the corrugating medium between thelap portions 5052 of the liners removed by a mill, the mill cutting thecorrugating media away from between the lap portions 50 and 52 up to thecorrugating media edge 54. The lap portions 50 and 52 are thereafteradhesively secured together by adhesive between the lap portions as at56, lap portion 52 being offset as at 53. While the blank progresses inthe direction of arrow A, the left hand edge portion 66 of the panel 22is subjected to roller or other suitable pressure to squeeze the linersat 60 and 62 together, breaking the corrugating media walls as at 64.The pressure applied is such as to reduce the thickness of thecorrugated fiberboard, on spring-back, by the actual combined thicknessof the two liner sheets forming the adhesively secured lap portions 50and 52. The area so pressed extends inwardly from the edge 66 to theoffset at 68. When the blank is slotted and creased or scored, the blankis ready for forming and folding into tubular form on the scores 23, 25,and 27, with the laps 50 and 52 folded on score line 29. The offsetsurface 70 of the liner at 60 between the offset 68 and edge 66, or theinside surface of the lap 52, or both surfaces, are coated withadhesive, and the double lap adhesively applied to the offset portion ofthe liner. Thereafter, the adhesive is allowed to set and the flushjoint created. The blank is then flattened to the form shown in FIGURES2 and 4 for the delivery in bundles to the customer.

While the invention has been described in regard to a blank wherein thecorrugations of the media extend parallel with the scores 23, 25, and27, which require the removal of the media between the lap portions 50and 52, the corrugations may extend in the other direction as, forexample, parallel with the flap scores 34 and 36. In such case, thecorrugating media may, in the formation of the blank at the corrugatingapparatus, be of sufficiently less width to provide lap portions withoutmedia therebetween, or the media may be removed from between the laparea by a mill running crosswise of the media flutes. The blank beforefolding and forming the joint will otherwise appear the same as theblank of FIGURE 1, except that the corrugations will extend in thedirection of the scores 34 and 36.

In practice, and as one example, each liner may be of a thickness of0.012 to 0.013 inch, while the corrugating medium is about .009 inchthick. Assuming the overall thickness of the corrugated board to be0.160 inch, the board is capable of being squeezed in the area 70 to athickness of 0.040 inch, following which, it will spring back to athickness of 0.130 inch, providing an offset at 68 of 0.030 inch,adequate to receive the two lap thicknesses 50 and 52 and provide asubstantially flush surface at the joint. The two liner thicknesses arereadily folded as at 29 to form the corner, and actual scoring for thefold may be light or unnecessary.

Where the corrugations extend parallel with the scores 23, 25, and 27,it will be seen that there is substantially no loss in strength at themanufacturers joint in a direction crosswise of the joint, since theeliminated corrugating media would not add appreciable strength to thetensile strength of the liners. While the joint has been shown ascompleted adjacent to a corner of the blank, the advantages of the jointwould be derived were the joint to be located between two corners anddisplaced from both.

While the flaps of panel 22 are reduced in thickness as at 72 and 74, noharm is done by such reduction, and in the finished box, such flaps maybe inside flaps if desired. On the other hand, should be offset beeffected by press action, rather than passage through rolls, the offsetarea could be reduced to that sufficient to accommodate the laps 50, 52,in which case, the flaps of panel 22 would be of full thickness and freeof crushed areas such as 72 and 74.

The joint thus formed is flush externally, and the interior of the boxexhibits no lapped members or other evidence of a joint and the raw edge66 is hidden from view when the box is erected. Whether the corrugationsextend parallel with the scores 23, 25, and 27, or parallel with thescores 34 and 36, it generally is the case that the grain of the linersextends crosswise of the corrugations and exhibits greatest strength inthe direction of the grain. Thus, the lap, being formed of thethicknesses of both liners, will exhibit substantial strength at thecorner, whether the grain extends crosswise or parallel with the cornerfold.

While a single embodiment with variations of the invention has beenillustrated and described, it is to be understood that the invention isnot limited thereto. Various changes in he construction and arrangementmay be made without departing from the spirit of the invention, as willbe apparent to those skilled in the art.

What is claimed is:

,1. A manufacturers joint for a box formed from a blank of corrugatedfiberboard having two liners and corrugating medium therebetween, saidjoint being formed between the two adjacent edges of a blank having aninner and an outer liner and intervening corrugating medium, one edge ofthe blank having the liners extended to form lap portions beyond theedge of the intervening corrugating medium, with the inner lap portionof the inner liner being offset outwardly and adhesively bonded to theouter liner to form a lap of the thickness of both liners and ofsubstantial width, and the other edge of the blank having its outerliner pressed inwardly along the edge for a width at least as great asthe width of the lap, to provide an offset area, and an offset at leastas great as the thickness of the lap, and said lap being secured to theoffset area in overlapping relation thereto.

2. A joint according to claim 1, wherein the lap is secured to theoffset area by an adhesive.

3. A joint as set forth in claim 1, wherein the lap is so folded atright angles adjacent to the other edge of the blank as to form a cornerof the box.

4. A joint as set forth in claim 1, wherein corrugating medium has beenremoved to form the lap portions and permit the inner lap portion to beoffset and adhesively bonded to the outer lap portion to form a lap oftwo thicknesses of the liner.

5. A joint according to claim 3, wherein the lap is secured to theoffset area by adhesive.

6. A joint according to claim 4, wherein the lap is secured to theoffset area by adhesive.

7. A joint according to claim 3, wherein the other edge nests in theoffset of the inner lap portion and is thereby concealed.

References Cited UNITED STATES PATENTS 1,101,928 6/1914 Hawkins et al.

1,417,776 5/1922 Shafer 22948 X 1,617,274 2/1927 Romer 22948 X 1,698,9081/1929 Cleveland 22948 1,731,111 10/1929 Romer 22948 2,333,676 11/1943Robinson 22948 X 3,145,131 8/1964 Finke 22948 X 3,245,604 4/1966 Chapman22948 3,341,104 9/1967 Loheed.

DAVIS T. MOORHEAD, Primary Examiner,

